This career development proposal details a plan for the Principal Investigator to obtain the training and experience necessary to develop an independent career as a clinical investigator. By conducting the proposed study, the PI will develop skills that will enable her to study the effects of exercise on insulin resistance in polycystic ovary syndrome (PCOS), and that will be relevant to many career pathways. PCOS is a common disorder affecting up to 10% of young women. It is characterized clinically by hirsutism and oligo/amenorrhea. Recent studies have documented significant insulin resistance in this population suggesting an important predisposition to long-term complications such as diabetes and cardiovascular disease. The early onset and large affected population create a powerful opportunity to harness the positive effects of lifestyle changes for purposes of disease prevention. However, the hirsutism and obesity associated with PCOS may create psychological barriers to change. For this reason, effective management may require a tailored approach that takes into account psychosocial issues as well as metabolic profile. Physical activity is an ideal intervention for this group. Exercise reduces insulin resistance, improves cardiovascular health and enhances sense of wellbeing. However, the type, duration and intensity of exercise that will optimally reduce insulin resistance, and that is well tolerated, has not been established. This study is meant to address these issues by answering the following questions about women with PCOS: 1. In a randomized controlled clinical trial, does a 12 week program of monitored exercise of moderate intensity, without weight loss, significantly improve insulin sensitivity as measured by an intravenous glucose tolerance test? What is the relative magnitude of the acute effect compared to the chronic effect of exercise on insulin sensitivity? 2. Does exercise that reduces insulin resistance also decrease androgen levels? 3. Does exercise improve indicators of perceived body image, quality of life, stress and depression?